This invention relates generally to apparatus for sequentially printing a message or code on a work piece and more particularly to such apparatus for moving a print head between a first position at a first orientation to a second position at a second, different orientation.
Moving a print head between inking and marking positions utilizing a fixed cam track with the print head having a first orientation at one end of the track where its ink supply is replenished and a different angular orientation at the other end of the track where it is brought into printing engagement with work piece is known. An example of this type mechanism is shown in U.S. Pat. No. 4,760,788. Typically, such mechanisms employ a print head support which mounts cam followers captured in the cam tracks and are caused to slide in the tracks as kinetic linkages move the print head support between the ends of the track. The sliding motion results in friction with concomitant wear and requires that the parts be relatively loose. This results in a mechanism in which the print head support is relatively unstable and adversely affects the quality of the printed characters on the work piece with regard to sharpness or definition. That is, due to the looseness of the print head support the printed characters tend to be fuzzy. The mechanism also tends to be noisy and gets nosier as the parts wear. The fuzziness of the printed characters also increases with wear of the parts. Further, due to friction and the looseness of parts with the forces impacting through the linkages the useful life of such mechanisms is relatively short.